Commit 664beed0 authored by Hugh Dickins's avatar Hugh Dickins Committed by Linus Torvalds
Browse files

[PATCH] unpaged: unifdefed PageCompound 



It looks like snd_xxx is not the only nopage to be using PageReserved as a way
of holding a high-order page together: which no longer works, but is masked by
our failure to free from VM_RESERVED areas.  We cannot fix that bug without
first substituting another way to hold the high-order page together, while
farming out the 0-order pages from within it.

That's just what PageCompound is designed for, but it's been kept under
CONFIG_HUGETLB_PAGE.  Remove the #ifdefs: which saves some space (out- of-line
put_page), doesn't slow down what most needs to be fast (already using
hugetlb), and unifies the way we handle high-order pages.

Signed-off-by: default avatarHugh Dickins <hugh@veritas.com>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent 1cdca61b

include/linux/mm.h

+0 −19
Original line number Diff line number Diff line
@@ -311,8 +311,6 @@ struct page { 


extern void FASTCALL(__page_cache_release(struct page *));



#ifdef CONFIG_HUGETLB_PAGE



static inline int page_count(struct page *page)

{

	if (PageCompound(page))
@@ -329,23 +327,6 @@ static inline void get_page(struct page *page) 


void put_page(struct page *page);



#else		/* CONFIG_HUGETLB_PAGE */



#define page_count(p)		(atomic_read(&(p)->_count) + 1)



static inline void get_page(struct page *page)

{

	atomic_inc(&page->_count);

}



static inline void put_page(struct page *page)

{

	if (put_page_testzero(page))

		__page_cache_release(page);

}



#endif		/* CONFIG_HUGETLB_PAGE */



/*

 * Multiple processes may "see" the same page. E.g. for untouched

 * mappings of /dev/null, all processes see the same page full of

include/linux/page-flags.h

+0 −4
Original line number Diff line number Diff line
@@ -287,11 +287,7 @@ extern void __mod_page_state(unsigned long offset, unsigned long delta); 
#define ClearPageReclaim(page)	clear_bit(PG_reclaim, &(page)->flags)

#define TestClearPageReclaim(page) test_and_clear_bit(PG_reclaim, &(page)->flags)



#ifdef CONFIG_HUGETLB_PAGE

#define PageCompound(page)	test_bit(PG_compound, &(page)->flags)

#else

#define PageCompound(page)	0

#endif

#define SetPageCompound(page)	set_bit(PG_compound, &(page)->flags)

#define ClearPageCompound(page)	clear_bit(PG_compound, &(page)->flags)

mm/page_alloc.c

+0 −5
Original line number Diff line number Diff line
@@ -148,10 +148,6 @@ static void bad_page(const char *function, struct page *page) 
	add_taint(TAINT_BAD_PAGE);

}



#ifndef CONFIG_HUGETLB_PAGE

#define prep_compound_page(page, order) do { } while (0)

#define destroy_compound_page(page, order) do { } while (0)

#else

/*

 * Higher-order pages are called "compound pages".  They are structured thusly:

 *
@@ -205,7 +201,6 @@ static void destroy_compound_page(struct page *page, unsigned long order) 
		ClearPageCompound(p);

	}

}

#endif		/* CONFIG_HUGETLB_PAGE */



/*

 * function for dealing with page's order in buddy system.

mm/swap.c

+0 −3
Original line number Diff line number Diff line
@@ -34,8 +34,6 @@ 
/* How many pages do we try to swap or page in/out together? */

int page_cluster;



#ifdef CONFIG_HUGETLB_PAGE



void put_page(struct page *page)

{

	if (unlikely(PageCompound(page))) {
@@ -52,7 +50,6 @@ void put_page(struct page *page) 
		__page_cache_release(page);

}

EXPORT_SYMBOL(put_page);

#endif



/*

 * Writeback is about to end against a page which has been marked for immediate

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